Diagnostic methods for branching catheter systems

ABSTRACT

Branching catheter systems with diagnostic components for detecting and isolating fluid flow problems (e.g., leaks, occlusions, etc.) and methods for detecting and isolating fluid flow problems are disclosed. Among the fluid flow problems that may potentially be detected are leaks in the branching catheter systems (e.g., cuts, disconnected components, etc.). Another fluid flow problem that may be detected using the diagnostic systems of the present invention is the presence of occlusions or other blockages that prevent fluid flow within the catheter systems. In addition to identifying that a problem exists, the diagnostic components may preferably also be used to identify the location of the fluid flow problem as discussed herein. Connectors for use in the branching catheter systems are also disclosed. Among the diagnostic components that may be used in branching catheter systems of the present are valves to control fluid flow through the various sections of the branching catheter system, fluid flow detectors to detect flow through the one or more sections of the branching catheter system and a control system for operating the diagnostic components.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/564,473, titled CATHETER SYSTEM HAVING FLOW RESTRICTION, ANDDIAGNOSTIC SYSTEM FOR USE WITH SAME, filed Apr. 22, 2004, which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates generally to implantable medical devicesand, more particularly, to branching catheter systems that includediagnostic components for detecting and isolating fluid flow problems(e.g., leaks, occlusions, etc.).

BACKGROUND

Implantable drug infusion systems are used to provide programmablelong-term delivery of a therapeutic agent, e.g., infusate drug, to atarget site such as the brain or the spinal canal or epidural space.These systems typically include a pump implanted at a remote location,e.g., within the abdominal or chest cavity, and a catheter tunneled fromthe pump to the target site. A drug may be delivered from a reservoir inthe pump to the target site via the catheter.

Some therapies, e.g., treatment of many neurological diseases, maybenefit from infusion of a therapeutic agent to multiple locationswithin the body. For instance, for the treatment of Parkinson's Disease,it may be beneficial to deliver a substance, e.g., Glial DerivedNeurotrophic Factor (GDNF), to both hemispheres of the brain(bilaterally). Infusing a drug to such multiple target sites istypically accomplished by separate infusion systems, e.g., a separatepump and catheter system for each target site. However, duplicatesystems result in not only increased costs and patient invasiveness (ascompared to single target site systems), but also increased complexitythat is inherent in such dual systems.

Branching catheter systems such as those described in, e.g., U.S. PatentApplication Publication No. US 2004/0199128 A1 (Morris et al.) andtitled CATHETER FOR TARGET SPECIFIC DRUG DELIVERY, have been developedto address some of the issues associated with using multiple systems fordelivering drugs to multiple locations within a patient.

SUMMARY OF THE INVENTION

The present invention is directed at branching catheter systems withdiagnostic components for detecting and isolating fluid flow problems(e.g., leaks, occlusions, etc.) and methods for detecting and isolatingfluid flow problems. Among the fluid flow problems that may potentiallybe detected are leaks in the branching catheter systems (e.g., cuts,disconnected components, etc.). Another fluid flow problem that may bedetected using the diagnostic systems of the present invention is thepresence of occlusions or other blockages that prevent fluid flow withinthe catheter systems. In addition to identifying that a problem exists,the diagnostic components may preferably also be used to identify thelocation of the fluid flow problem as discussed herein.

Among the diagnostic components that may be used in branching cathetersystems of the present are valves to control fluid flow through thevarious sections of the branching catheter system, fluid flow detectorsto detect flow through the one or more sections of the branchingcatheter system and a control system for operating the diagnosticcomponents.

In some embodiments, the diagnostic components may preferably include asupply valve to control flow to all of the branches of the branchingcatheter and branch valves in each of the branches to control the flowof fluid into the selected branch. The valves may preferably operate asshut-off valves to occlude flow at the their location within thebranching catheter system.

The flow detector may preferably be positioned and operable to detectfluid flow delivered by a pump mechanism. The flow detector may take avariety of different forms, e.g., a pressure sensor operable to sensepressure at a location within the catheter system (where pressure isindicative of flow), a flow sensor operable to detect fluid movingthrough a lumen (e.g. a mass flow sensor), etc.

Branching catheter systems that incorporate diagnostic components of thepresent invention may preferably include a branching catheter connectorthat includes an inlet port and two or more outlet ports in fluidcommunication with the inlet port. Each of the outlet ports maypreferably feed fluid into a branch of the branching catheter system,while the inlet port may preferably be adapted to receive fluid from apump mechanism operably connected to a reservoir containing a supply ofa drug to be delivered to a patient.

Although it may be preferred that the branching catheter systems includediagnostic components such as valves to control fluid flow past aselected point, methods of the present invention may alternativelyinvolve manual occlusion of lumens at selected locations within thebranching catheter systems. For example, occlusion may involve manualcompression of a catheter at a selected location such that the catheteris pinched at that location.

In another embodiment, a method for detecting and isolating leaks andocclusions in a branching catheter system is provided. The method mayinclude detecting a change in a characteristic, e.g., pressure, of afluid within the system. Valves associated with one or more of an inletport, a first outlet port, and a second outlet port of a branchingconnector of the system may be activated independently to disrupt flowthrough one or more sections of the system. The method may also includemonitoring fluid flow (e.g., pressure) after valve activation; anddetermining a location of a catheter leak and/or occlusion based uponthe pressure detected.

To assist in diagnosis of fluid flow problems in branching catheters, itmay be preferred to include flow restrictors at selected locationswithin the branching catheters. In addition to assisting with diagnosisof fluid flow problems, the flow restrictors may also be useful forbalancing flow between different branches in a branching cathetersystem.

Branching catheter systems including diagnostic components in accordancewith the present invention or methods of the present invention mayprovide intuitive and systematic techniques, in conjunction withappropriate hardware, for troubleshooting infusion systems includingimplantable branching catheter systems. For example, the systems and/ormethods as described herein may be used to detect catheter failures aswell as identify failure locations in branching catheter systems. Inother words, these systems and/or methods may enable not only detectionof a catheter failure, e.g., the presence of a leak or clog, but mayalso isolate that failure to a particular section (i.e., supply catheteror specific branch catheter) of the branching catheter system.

The systems and/or methods of the present invention may also allowconfirmation of successful implantation while the patient is still onthe operating table. Moreover, revision surgeries to correct problemscan be focused to the appropriate component(s) of the system, thusmaking surgery potentially less invasive and time consuming.

In addition to potentially increased robustness of the implant procedureand potentially improved ability to focus repairs/revisions, the systemsand/or methods as described herein may also reduce the risk of patientover/under dosing. Moreover, these systems and/or methods may decreasethe number of instances of therapies that might be inappropriatelydiscontinued as “inefficacious” or classified as “marginallyefficacious.” By using the feedback provided by systems and/or methodsof the present invention, physicians may further be able to developimprovements in implant technique and hardware design.

In one embodiment, a flow restrictor for use with an implantablecatheter of the present invention may include an elongate male memberhaving a helical groove formed in an outer surface thereof. The flowrestrictor may fit with interference within a lumen of a catheter orother device or, alternatively, may fit with interference inside aseparate sheath, wherein the combined restrictor/sheath may then beinserted within the catheter lumen.

The fluids delivered using the present invention may preferably containone or more drugs. A drug of the present invention may include atherapeutic substance. Other substances may or may not be intended tohave a therapeutic effect and are not easily classified, such as, e.g.,saline solution, fluoroscopy agents, disease diagnostic agents, etc.Unless otherwise noted in the following paragraphs, the term “drug” asused herein may include any therapeutic, diagnostic, or other substancethat is delivered using the implantable medical devices of the presentinvention. The drugs will typically be fluids (e.g., liquids) orcontained in fluid carriers (e.g., liquid carriers) as either solutionsor mixtures.

Therapeutic substances delivered using the present invention maypreferably be intended to have a therapeutic effect such aspharmaceutical compositions, genetic materials, biologics, and othersubstances. Pharmaceutical compositions are typically chemicalformulations intended to have a therapeutic effect such as intrathecalantispasmodics, pain medications, chemotherapeutic agents, and the like.Pharmaceutical compositions may be configured to function in animplanted environment with characteristics such as stability at bodytemperature to retain therapeutic qualities, concentration to reduce thefrequency of replenishment, and the like. Genetic materials includesubstances intended to have a direct or indirect genetic therapeuticeffect such as genetic vectors, genetic regulator elements, geneticstructural elements, DNA, and the like. Biologics include substancesthat are living matter or derived from living matter intended to have atherapeutic effect such as stem cells, platelets, hormones, biologicallyproduced chemicals, and the like.

In one aspect, the present invention provides an implantable branchedcatheter system that includes a supply catheter section having aproximal end and a distal end and two or more delivery branches in fluidcommunication with the distal end of the supply catheter section. Eachdelivery branch of the two or more delivery branches includes a deliverycatheter section having a proximal end and a distal end along with aflow restrictor located along the delivery catheter section, wherein theflow restrictor restricts flow through the delivery catheter section.Each delivery branch further includes a branch valve located between thedistal end of the supply catheter section and the proximal end of thedelivery catheter section. The system also includes a supply valvelocated proximate the distal end of the supply catheter section, whereinthe supply valve controls flow through the distal end of the supplycatheter section; and a flow detector located proximate the proximal endof the supply catheter section, wherein the flow detector detects flowthrough the supply catheter section.

In another aspect, the present invention provides an implantablebranched catheter system that includes a supply catheter section havinga proximal end and a distal end and two or more delivery branches influid communication with the distal end of the supply catheter section.Each delivery branch of the two or more delivery branches includes adelivery catheter section having a proximal end and a distal end; a flowrestrictor located proximate a distal end of the delivery cathetersection, wherein the flow restrictor restricts flow through the deliverycatheter section; and a branch valve located between the distal end ofthe supply catheter section and the proximal end of the deliverycatheter section. The system further includes a supply valve locatedproximate the distal end of the supply catheter section, wherein thesupply valve controls flow through the distal end of the supply cathetersection and a bleeder valve located proximate the distal end of thesupply catheter section, wherein the bleeder valve is located distal ofthe supply valve, and wherein the bleeder valve shunts flow out of thebranched catheter system. The system also includes a flow detectorlocated proximate the proximal end of the supply catheter section,wherein the flow detector is a pressure sensor.

In another aspect, the present invention provides a branching catheterconnector for use in an implantable branching catheter system, theconnector including an implantable connector body defining a fluid pathhaving a branch point at which the fluid path separates into two or morebranches; an inlet port located within the connector body, the inletport in fluid communication with the fluid path; two or more outletports in fluid communication with the inlet port through the branchingfluid path, wherein the branch point is located between the inlet portand the two or more outlet ports; a supply valve located proximate theinlet port, wherein the supply valve is located in the branching fluidpath between the inlet port and the branch point; and a branch valvelocated proximate each outlet port of the two or more outlet ports,wherein the branch valve of each outlet port is located in the fluidpath between the branch point and the outlet port.

In another aspect, the present invention provides a method of diagnosingflow conditions in a branched catheter system. The method includesproviding an implantable branched catheter system that includes a supplycatheter section having a proximal end and a distal end, wherein movingfrom the proximal end towards the distal end defines a downstreamdirection within the system and wherein moving from the distal endtowards the proximal end defines an upstream direction within thesystem. The system further includes a flow detector located proximatethe proximal end of the supply catheter section, wherein the flowdetector detects flow through the supply catheter section; and two ormore delivery branches in fluid communication with the distal end of thesupply catheter. Each delivery branch of the two or more deliverybranches includes a delivery catheter section having a proximal end anda distal end, and wherein each delivery branch of the two or moredelivery branches includes a flow restrictor located within the deliverybranch, wherein the flow restrictor restricts flow through the deliverycatheter section. The method further includes delivering fluid into theproximal end of the supply catheter section; and monitoring the flowdetector while delivering the fluid and while selectively occluding flowthrough one or more of the supply catheter section and the deliverycatheter sections.

In another aspect, the present invention provides a method of diagnosingflow conditions in a branched catheter system. The method includesproviding an implantable branched catheter system that includes a supplycatheter section having a proximal end and a distal end, wherein movingfrom the proximal end towards the distal end defines a downstreamdirection within the system and wherein moving from the distal endtowards the proximal end defines an upstream direction within thesystem. The system further includes a flow detector located proximatethe proximal end of the supply catheter section, wherein the flowdetector detects flow through the supply catheter section; and two ormore delivery branches in fluid communication with the distal end of thesupply catheter. Each delivery branch of the two or more deliverybranches includes a delivery catheter section having a proximal end anda distal end, and wherein each delivery branch of the two or moredelivery branches includes a flow restrictor located proximate a distalend of the delivery branch, wherein the flow restrictor restricts flowthrough the delivery catheter section. The method further includesdelivering fluid into the proximal end of the supply catheter section;and monitoring the flow detector while delivering the fluid and whileselectively occluding flow through one or more of the supply cathetersection and the delivery catheter sections. The method further comprisesselectively shunting the fluid delivered into the supply cathetersection outside of the system before the fluid enters the two or moredelivery branches while monitoring the flow detector

The above summary is not intended to describe each embodiment or everyimplementation of the present invention. Rather, a more completeunderstanding of the invention will become apparent and appreciated byreference to the following Detailed Description of Exemplary Embodimentsin view of the accompanying figures of the drawing.

BRIEF DESCRIPTIONS OF THE FIGURES.

The present invention will be further described with reference to thefigures, wherein:

FIG. 1 is a diagrammatic representation of an implanted branchingcatheter system in accordance with one embodiment of the invention;

FIG. 2 is a schematic diagram of one exemplary branching catheter systemaccording to the present invention;

FIG. 3 is a schematic diagram of another exemplary branching cathetersystem according to the present invention;

FIG. 4 is a schematic diagram of another exemplary branching cathetersystem according to the present invention; and

FIG. 5 is a flow chart illustrating an exemplary method of identifyingand locating a fluid flow problem within the branching catheter systemof FIG. 4;

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following detailed description of illustrative embodiments of theinvention, reference is made to the accompanying figures of the drawingwhich form a part hereof, and in which are shown, by way ofillustration, specific embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand structural changes may be made without departing from the scope ofthe present invention.

Catheter cuts, occlusions, kinks, and improper (e.g. leaking)connections together may represent a substantial portion of clinicalcomplications with current implantable infusion systems. Such problemsmay be aggravated for infusion systems delivering drugs to one or morelocations (e.g., branching catheter systems) that utilize a fixed ratepump because, for example, complete occlusion of one distal branch couldresult in the delivery of the full balance of the drug to the otherbranch. Normal techniques of detecting an occlusion in a single cathetersystem, such as syringe extraction of the reservoir volume andsubsequent comparison of the same to the expected volume, would beinaccurate in these circumstances as the appropriate volume would stillbe dispensed, albeit to only a single side. Embodiments of the presentinvention as described herein preferably enable reliable diagnosis ofthe above-mentioned problems, whether they were induced immediately as ainadvertent consequence of implantation, or occurred during the courseof therapy.

FIG. 1 illustrates an exemplary implanted branching catheter system 10in accordance with one embodiment of the invention. The system 10 mayinclude a device, e.g., a pump 20, implanted in an abdominal region of apatient, and a proximal infusion catheter 22, coupled to the pump 20 viaa connector 24. The proximal catheter 22 may extend into the head of thepatient, where fluid flow may be divided into two branches 30 and 40,with each branch including a branch catheter implanted to deliver thefluid to separate areas of the brain.

Although the embodiment of FIG. 1 includes a bifurcating cathetersystem, the present invention may include catheter systems with three ormore branches. In other variations, although the depicted system isimplanted for delivery into the brain of a patient, it should beunderstood that branching catheter systems of the present invention maybe used to deliver fluids to other areas of the body.

Furthermore, although the pump 20 is depicted as implanted within theabdominal cavity, it may alternatively be implanted in any suitablelocation, e.g., in the chest cavity, cranially, etc. In some instances,the pump mechanism itself may not even be implanted, i.e., the pump 20may be located externally of the patient's body, with the catheter 22used to deliver the fluid internally.

The pump 20 may include a reservoir to hold a volume of fluid that maypreferably contain one or more drugs. The reservoir may be periodicallyrefilled via an injection port (not shown), and a pump mechanism (e.g.,pressurized bladder, peristaltic pump, piston pump, etc.) provided maypropel the fluid through the proximal catheter 22 and into the branches30 and 40. While not wishing to be bound to any particularconfiguration, the pump 20 may be a SYNCHROMED II manufactured byMedtronic, Inc., of Fridley, Minn., USA.

The pump 20 may further include a flow detector 26, e.g., a pressuresensor. The pressure sensor may be similar to that described in U.S.Patent Application Publication No. US 2005/0075624 A1, entitled“Pressure Sensor for Medical Device” (see also: U.S. patent applicationSer. No. 10/691,814, filed 23 Oct. 2003, and entitled “Method forMonitoring Bolus Delivery;” U.S. Pat. No. 6,551,290, entitled “Catheterfor Target Specific Drug Delivery;” and U.S. patent application Ser. No.09/625,751, filed 26 Jul. 2000, and entitled “Catheter for TargetSpecific Drug Delivery”). Alternatively, the flow sensing device coulddetect fluid flow directly using any appropriate flow detectiontechnologies.

FIGS. 2 & 3 are schematic diagrams of two examples of branching cathetersystems according to the present invention. The various components ofthe two branching catheter systems will be described below, followed bya description of a third example depicted in FIG. 4. Operation of abranching catheter system and its diagnostic components will bedescribed with respect to the system depicted in FIG. 4.

The branching catheter system 100 of FIG. 2 includes a supply catheter122 that leads to two branches with branch catheters 130 and 140. Thesupply catheter 122 of the branching catheter system 100 is depicted asattached to a pump 120, although it should be understood that thebranching catheter systems of the present invention may be suppliedindependently of the pump mechanisms used to deliver fluids into thebranching catheter systems.

Although described herein as catheters, it should be understood that thesupply catheters and delivery catheters or branch catheters of someembodiments may be sections of a branching catheter system as opposed toseparate independent components assembled into the branching cathetersystems. In other words, the different catheters may be sections of anintegrally formed catheter system. Alternatively, one or more of thedifferent catheters may be provided as separate components that areassembled to provide a branching catheter system according to thepresent invention.

As discussed herein, the pump 120 may take any suitable configurationand may preferably include a reservoir containing a drug for delivery toa patient. Also depicted in FIG. 2 is a flow detector 126 used to detectflow into the branching catheter system 100. The flow detector 126 isdepicted as integral with the pump mechanism 120, although it may beprovided separately from the pump 120. It may, however, be preferredthat the flow detector 126 (if separate from the pump 120) be locatedclose to the pump 120, because, as discussed herein, diagnostics cantypically be performed only on components of the branching cathetersystem that are located downstream of the flow detector 126.

The system 100 of FIG. 2 also includes valves used to control fluid flowwithin the system. It may be preferred that the valves prevent flow whenclosed, although in some instances, it may be sufficient if some smallamount of fluid passes through the valves when closed. The depictedsystem 100 includes a supply valve 128 that is preferably locatedproximate the distal end of the supply catheter 122. Branch valves 138and 148 are located within each of the branches 130 and 140,respectively. It may be preferred that the branch valves 138 and 148 belocated as close as possible to the branch point 102 at which fluid isdivided to flow into the branch catheters 130 and 140.

Each of the branches 130 and 140 may also preferably include a flowrestriction 132 and 142, respectively. The flow restrictors maypreferably serve to: a) ensure balanced delivery of infusate (fluid)through the branches of the system; and/or b) provide sufficientbackpressure to ensure robust detection of fluid flow problems such ascuts/occlusions. Further discussions regarding the use of flowrestrictors in branched catheters may be found in U.S. PatentApplication Publication No. US 2004/0199128 A1 (Morris et al.), entitledCATHETER FOR TARGET SPECIFIC DRUG DELIVERY. As described therein, theflow restrictors may be in the form of a component that functions toboth provide flow restriction and deliver a drug to a selected bodylocation (using, e.g., a permeable membrane, small orifices, etc.).Alternatively, fluid delivery out of the catheter and flow restrictionof fluid moving through the catheter may be performed by separatecomponents.

The term “flow restrictor” as used herein, is intended to represent aflow resistance that is added to a system to bring the total flowresistance above a specified value; it does not necessarily refer to asingular component. For example, two “flow restrictors” (i.e. twocomponents) of equal resistance placed in series at the tip of a givencatheter could be functionally equivalent to a single flow restrictorwhose resistance is twice that of either of the serial flow restrictorstaken by itself.

The various components such as valves, pumps, etc. in systems accordingto the present invention may be controlled by any suitable controllerthat may be implanted in or located outside of the body of the patient.For example, the controller may be located within the pump 120 orexternal thereto and connected to the various components by wires,optical fibers, etc. Control may also be effected by the use oftelemetry, which may be used for communication between components and auser, for external programming etc. Telemetry control devices, systemsand methods that may be adapted for use in connection with the presentinvention may be described in, e.g., U.S. Pat. No. 5,558,640 (Pfeiler etal.); U.S. Pat. No. 5,820,589 (Torgerson et al.); and U.S. Pat. No.5,999,857 (Weijand et al.).

Also depicted in broken lines in FIG. 2 is a branching catheterconnector 160 that may be used in connection with branching cathetersystems of the present invention. The connector 160 may house the supplyvalve 128 and branch valves 138 and 148, as well as the branch point 102at which fluid flowing through the system 100 is divided for delivery tothe different branches 130 and 140.

The body of the connector 160 may, in one embodiment, be made frommolded silicone (e.g., Nu-Sil MED 4870 LSR, 65-75 Shore A durometer).This material may provide certain potentially desirable benefits, e.g.,desirable material properties such as elastic and creep characteristics,at a relatively low cost. However, other biocompatible materials such asETR silicone, urethane, polyurethane, etc., are also possible withoutdeparting from the scope of the invention.

Use of the connector 160 may be advantageous in that the connector 160may be provided as an independent component that can be assembled withexisting catheters to form a branching catheter system according to thepresent invention. As a result, an existing catheter or tubing may beused as the supply catheter 122 connecting the pump 120 to the inletport 162 of the connector 160. Similarly, existing catheters may also beconnected to the outlet ports 164 and 166 of the connector to providebranch catheters 130 and 140. The connector 160 may preferably define afluid path that includes the branch point 102, inlet port 162 and outletports 164 and 166. The various valves may preferably be distributedalong the fluid path as defined within the connector 160. For example, ableeder valve (see ZA2 in FIG. 4) may be located in the fluid pathbetween the supply valve 128 and the branch point 102. Similarly acontroller may be operatively connected to the valves and othercomponents in the connectors of the present invention.

FIG. 3 is a schematic diagram of another branching catheter system 200that includes more than two branches. The branching catheter system 200is attached to a pump mechanism 220 using a supply catheter 222. A flowdetector 226 is located proximate the proximal end of the supplycatheter 222. In this embodiment, the flow detector 226 is depicted asseparate from the pump mechanism 220.

The supply catheter leads to the first branch point 202 at which thefluid flow separates into two branch catheters 270 and 280. A supplyvalve 228 is, however, preferably located upstream of the branch point202. As with branching catheter system 100, it may also be preferredthat the valve 228 be located proximate the distal end or downstream endof the supply catheter 222.

An optional component depicted in the branching catheter system 200 is ableeder valve 229. The bleeder valve 229 preferably functions to preventflow to the branch point 202 and also to shunt or divert flow out of thebranching catheter system 200. Use of the bleeder valve 229 may allowfor the detection of an occlusion in the supply catheter 222 locatedbetween the flow detector 226 and the bleeder valve 229 as describedelsewhere herein. Although the valve 228 and bleeder valve 229 aredepicted as separate components, it will be understood that they may beintegrated into a single valve mechanism (e.g., a three port valve) thatcan perform the functions of both valves 228 and 229.

The branching catheter system 200 also includes branch valves 274 and288 downstream of the branch point 202. It may be preferred that thebranch valves 274 and 288 be capable of shutting off or occluding flowinto their respective branch catheter 270 or 280. As a result, it may bepreferred that the branch valves 274 and 288 be located as close aspossible to the upstream or proximal ends of the branch catheters 270and 280 such that the branch catheters can be isolated from thebranching catheter system 200.

Branch catheter 280 in the depicted branching catheter system 200 alsopreferably includes a flow restrictor 282. It may be preferred that theflow restrictor 282 be located proximate the distal end of the branchcatheter 280 as depicted in FIG. 3.

Branch catheter 270 in the depicted branching catheter system 200 leadsto a second branch point 204 from which branch catheters 230 and 240extend. As a result, the branch catheter 270 may function in manyrespects like supply catheter 222. For example, the branch catheter 270may also preferably include a valve 278 proximate its distal ordownstream end, i.e., the end at which fluid flow is divided by thebranch point 204. The branch catheter 270 may also preferably include ableeder valve 279 proximate its distal end similar to the supplycatheter 222. As with supply catheter 222, the valve 278 and bleedervalve 279 are depicted as separate components, although it will beunderstood that they may be integrated into a single valve mechanism(e.g., a three port valve) that can perform the functions of both valves278 and 279.

Branch valves 238 and 248 are preferably provided within each of thebranch catheters 230 and 240, respectively, downstream from the branchpoint 204. It may be preferred that the branch valves 238 and 248 belocated as close as possible to the branch point 204 at which fluid isdivided to flow into the branch catheters 230 and 240. Each of thebranch catheters 230 and 240 may also preferably include a flowrestrictor 232 and 242, respectively. It may be further preferred thatthe flow restrictors be located at or near the distal ends of the branchcatheters 230 and 240.

The branching catheter system 200 include three delivery branches inbranch catheters 230, 240 and 280. As discussed above, it may bepreferred that each of the branch catheters include a flow restrictor232, 242, and 282 (respectively). If it is desired that the amount offluid (i.e., drug) to be delivered from each of the three branches is tobe roughly equal, the flow restrictors may not necessarily be identical.It may be necessary, for example, to consider the effects of the valvesand the length of the fluid flow path through the different cathetersand adjust the amount of flow restriction provided in each of thebranches to balance flow therethrough.

FIG. 4 s a schematic diagram of another branching catheter system 300including diagnostic components that is attached to a pump 320. Fluid isdelivered to the branching catheter system 300 using a proximal orsupply catheter 322 that may preferably be connected to an inlet port362 of a branching catheter connector 360. The pump 320 may preferablyinclude a flow detector 326, e.g., a pressure sensor operable to monitorpump output pressure. The proximal catheter 322 may be fluidly coupled,via the connector 360, to a left outlet port 364 that is, in turn,coupled to a first or left branch catheter L. The proximal catheter 322may also be coupled, via the connector 360, to a right outlet port 366that is, in turn, coupled to a second or right branch catheter R.

A flow restrictor 310 may preferably be located near a distal end ofeach branch catheter L and R. As described above, the flow restrictorsmay preferably serve to: a) ensure balanced delivery of infusate to thetarget regions; and/or b) provide sufficient backpressure to ensurerobust detection of cuts/occlusions by the pressure sensor.

Along with the flow detector 326 and the flow restrictors 310, thediagnostic system may include a series of valves to assist in thediagnosis of fluid flow problems within the branching catheter system300. In the embodiment of branching catheter system 300 depicted in FIG.4, valves ZA1 (located proximate the inlet port 362 of the connector360), ZB (located in the left outlet port 364 of connector 360), and ZC(located in the right outlet port 366 of connector 360) may preferably,when activated, impede flow (and more preferably prevent flow past thevalve). For example, the valves may preferably be pinch-type, shut-offvalves, although any suitable valve construction may be used.

Also, although the valves may preferably be used while performingmethods of the present invention, it should be understood that themethods may alternatively be performed using manual pressure on aselected segment of catheter tubing down (against a hard surface, e.g.,the cranium) in order to block flow.

Optional valve ZA2 as seen proximate the inlet port 362 of the connector360 may preferably be a bleeder valve. That is, when activated, valveZA2 may preferably both shut off flow downstream of the valve and shuntthe flow path outside the catheter system 300, e.g., into surroundingtissue. In some embodiments, the shut-off feature of valve ZA2 may beeliminated, i.e., it may function as a bleeder valve only. In otherembodiments, valve ZA2 could be eliminated altogether. If no bleedervalve is present, methods as described below in which the bleeder valveZA2 is activated could alternatively be practiced by, e.g., unplugging(disconnecting) the supply catheter 322 from the connector 360).However, by providing the bleeder valve ZA2, a physician may preferablyhave the ability to perform a wide range of diagnostics without havingto perform, e.g., subcutaneous cut-down to access the proximal catheter322 to disconnect it manually.

In some embodiments in which, e.g., the branching catheter system 300 isimplanted cranially, the valves ZA1, ZA2, ZB, and ZC may preferably befelt beneath the skin of the scalp after implantation. In such asituation, the valves may be actuated by manually compressing the valveagainst a surface such as the cranium or other surface that allows forsufficient compression to close the valve.

Valves ZA1-ZC could be configured as separate metal or plasticcomponents located inside the respective ports of the connector 360.Alternatively, the valves could be integrally formed with the connector360, e.g., as part of the molded structure itself. Shunting hardware formanaging hydrocephalic patients provide examples of the latter.

In FIG. 4, reference letters A, B, C, D, E, F, G, H, and I are used toidentify catheter fluid flow status. In particular, reference letters A,D, and G are used to identify a cut in the supply catheter 322, the leftcatheter L, and the right catheter R, respectively. Similarly, referenceletters B, E, and H are used to identify an occlusion in the supplycatheter 322, the left catheter L, and the right catheter R,respectively. Finally, reference letters C, F, and I are used toidentify the supply catheter 322, the left catheter L, and the rightcatheter R, respectively, as being normal or intact.

The configuration of the branching catheter system 300 depicted in FIG.4 permits twenty-seven (27) possible status combinations, i.e.,combinations of cuts, occlusions, and intact (free of cuts orocclusions) catheter portions. These combinations are presented intabular form in Table I. Each status combination can be distinguishedfrom the others by some set of user actions. For example, FIG. 5illustrates a flow chart describing the sensor states and user actionsof Table I, as well as the resulting conclusions that may be drawntherefrom. However, these cases are not a unique set. For example,redundant (i.e. unnecessary or inconclusive actions) might be performedbefore entering one of the paths shown in the flow chart of FIG. 5.

TABLE I User Action(s) Supply Left (Activated Valve(s)) → Leg Leg RightInitial Sensor Corresponding Case (322) (L) Leg (R) State (326) SensorResponse(s) 1 A D G TO ZERO Z_(A1) → TO ZERO 2 A D H TO ZERO Z_(A1) → TOZERO 3 A D I TO ZERO Z_(A1) → TO ZERO 4 A E G TO ZERO Z_(A1) → TO ZERO 5A E H TO ZERO Z_(A1) → TO ZERO 6 A E I TO ZERO Z_(A1) → TO ZERO 7 A F GTO ZERO Z_(A1) → TO ZERO 8 A F H TO ZERO Z_(A1) → TO ZERO 9 A F I TOZERO Z_(A1) → TO ZERO 10 B D G TO MAX Z_(A2) → TO MAX 11 B D H TO MAXZ_(A2) → TO MAX 12 B D I TO MAX Z_(A2) → TO MAX 13 B E G TO MAX Z_(A2) →TO MAX 14 B E H TO MAX Z_(A2) → TO MAX 15 B E I TO MAX Z_(A2) → TO MAX16 B F G TO MAX Z_(A2) → TO MAX 17 B F H TO MAX Z_(A2) → TO MAX 18 B F ITO MAX Z_(A2) → TO MAX 19 C D G TO ZERO Z_(A1) → TO MAX; Z_(B) → TOZERO; Z_(C) → TO ZERO 20 C D H TO ZERO Z_(A1) → TO MAX; Z_(B) → MAX 21 CD I TO ZERO Z_(A1) → TO MAX; Z_(B) → TWICE BASELINE 22 C E G TO ZEROZ_(A1) → TO MAX; Z_(C) → MAX 23 C E H TO MAX Z_(A2) → TO ZERO 24 C E ITWICE Z_(C) → TO MAX BASELINE 25 C F G TO ZERO Z_(A1) → TO MAX; Z_(C) →TWICE BASELINE 26 C F H TWICE Z_(B) → TO MAX BASELINE 27 C F I BASELINEBASELINE

The following examples may illustrate an exemplary procedure forutilizing the diagnostic system illustrated in FIG. 4. Once implanted,the flow detector 326 of the branching catheter system 300 may beinterrogated, e.g., via telemetry or other techniques, to ascertain whatis referred to herein as an “initial sensor state.” It may, for example,be desirable to interrogate the flow detector 326 during or immediatelyafter implantation to ensure that the branching catheter system 300 isintact and functional. Similarly, it may be beneficial over the courseof treatment to interrogate the flow detector 326 of the branchingcatheter system 300 if patient response indicates a potential problem.

Where the flow detector 326 is a pressure sensor and the pump 320 isoperating to deliver fluid through the branching catheter system 300,the initial sensor state is preferably equivalent to the baselinepressure (the predetermined pressure for which the branching cathetersystem 300 was intended to operate) as represented by the first columnof the flow chart depicted in FIG. 5 and summarized as case 27 in TableI. In that state, it may be concluded that catheter flow is normal andthere are no occlusions or cuts in the supply catheter 322 or the branchcatheters L & R.

However, where the initial sensor state is at or near maximum (i.e., ator near the maximum pressure output of the pump 320) as shown in thesecond column of the flowchart of FIG. 5; is about twice the baselinepressure as shown in the third column of FIG. 5; or is at or near zeropressure as shown in the fourth column of FIG. 5, additional valveactivation/manipulation may reveal the existence of a fluid flow problemwithin the branching catheter system 300 (e.g., catheter cut orocclusion). If the flow detector and valves are in the preferredlocations as discussed herein, it may also be possible to identify thegeneral location of the fluid flow problem (e.g., in the supply catheter322 and/or branch catheters L & R).

For instance, where the flow detector 326 is a pressure sensor and theinitial sensor state is “at or near maximum,” the physician may activatevalve ZA2 to shunt flow though the supply catheter 322 out of thebranching catheter system 300 and monitor the response of the flowdetector 326 (which, as discussed above, may preferably be a pressuresensor). If the sensor reading remains at or near maximum afteractivation of bleeder valve ZA2, it may be concluded that an occlusionis present in the supply catheter 322 that prevents or substantiallyimpedes flow through the supply catheter 322. However, where theactivation of bleeder valve ZA2 results in a pressure reading at or nearzero, then it may be concluded that there is an occlusion in both theleft and right branch catheters L & R.

A more involved interrogation is illustrated by the fourth column ofFIG. 5 where an initial sensor state of a flow detector 326 in the formof a pressure sensor is “at or near zero.” If the physician activatessupply valve ZA1 and the reading does not change, it may be concludedthat there is a cut in the supply catheter 322 (or the supply catheter322 is disconnected at either end). Yet if activation of supply valveZA1 results in a subsequent pressure reading that is at or near maximumpressure of the pump 320, the physician may proceed to activate branchvalve ZB.

If activation of branch valve ZB as depicted in the fourth columnresults in a third pressure reading that is “at or near zero,” thenbranch valve ZC may be activated, whereupon the identified sensorresponses and resulting catheter failures (“conclusions”) may beidentified as shown in FIG. 5. If, after activation of branch valve ZC,the fourth pressure reading is “twice baseline,” then it may beconcluded that there is a cut in the right branch catheter R.Alternatively, if activation of branch valve ZC results in a sensorreading of “at or near max” then it may be concluded that the leftbranch catheter L is occluded and that the right branch catheter Rincludes a cut (or is disconnected from the system 300). In anotheralternative, activation of branch valve ZC may result in a sensorreading of “at or near zero.” In that situation, it may be concludedthat both of the left and right branch catheters L & R are either cut ordisconnected from the branching catheter system 300.

Still in the fourth column of the flow chart of FIG. 5, if the thirdpressure reading (after activation of branch valve ZB) is “at or nearmax” then it may be concluded that there is an occlusion in the rightbranch catheter R and a cut in the left branch catheter L (ordisconnection of the left branch catheter L from the system 300).Alternatively, if activation of branch valve ZB in the fourth column ofthe flow chart of FIG. 5 results in a third sensor reading of “twicebaseline” then it may be concluded that the left branch catheter L iseither cut (or disconnected from the system 300).

It should be noted that, after activating supply valve ZA1 and noting anincrease in the sensor response to “at or near maximum” (as the secondsensor reading) a user could choose to activate branch valve ZC insteadof branch valve ZB as the subsequent action. In this case, activatingbranch valve ZB would be the third user action, and the resultingconclusions depicted in column four of the flowchart could be revised tosubstitute “left” for “right” and vice versa.

Although flow restrictors 310 located in the branch catheters(preferably proximate the distal end or tip of the branch catheters) mayfacilitate robust detection of fluid flow problems using a pressuresensor and may additionally be used to control (e.g., equalize) flowthrough the different branch catheters, diagnostic systems in accordancewith other embodiments of the present invention could be implementedwithout the use of such flow restrictors. Moreover, while describedherein in the context of pressure sensors, it is contemplated that otherflow detectors, e.g., flow sensors, could also be used.

Furthermore, if only the detection of occlusions were desirable, (i.e.,no desire to detect catheter cuts or disconnections), then left andright restrictors 310 could be located anywhere downstream of the branchvalves along the length of the respective left and right branchcatheters L and R, rather than near the distal ends/tips of the branchcatheters.

If provided, flow restrictors used in the branching catheter systems ofthe present invention may take any suitable form, some examples of whichmay be described in U.S. Patent Application Publication No. US2004/0199128 A1 (Morris et al.), entitled CATHETER FOR TARGET SPECIFICDRUG DELIVERY; as well as in the priority application on which thepresent application is based (U.S. Provisional Application No.60/564,473, titled CATHETER SYSTEM HAVING FLOW RESTRICTION, ANDDIAGNOSTIC SYSTEM FOR USE WITH SAME, filed Apr. 22, 2004); and inco-pending U.S. patent application Ser. No. 11/112,007, titled CATHETERSYSTEMS HAVING FLOW RESTRICTORS, filed on even date herewith.

As used herein and in the appended claims, the singular forms “a,”“and,” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a” or “the”component may include one or more of the components and equivalentsthereof known to those skilled in the art.

The complete disclosure of the patents, patent documents, andpublications cited in the Background, the Detailed Description ofExemplary Embodiments, and elsewhere herein are incorporated byreference in their entirety as if each were individually incorporated.

Illustrative embodiments of this invention are discussed and referencehas been made to possible variations within the scope of this invention.These and other variations and modifications in the invention will beapparent to those skilled in the art without departing from the scope ofthe invention, and it should be understood that this invention is notlimited to the illustrative embodiments set forth herein.

1. A method of diagnosing flow conditions in a branched catheter system,the method comprising: providing an implantable branched catheter systemcomprising: a supply catheter section comprising a proximal end and adistal end, wherein moving from the proximal end towards the distal enddefines a downstream direction within the system and wherein moving fromthe distal end towards the proximal end defines an upstream directionwithin the system; a flow detector located proximate the proximal end ofthe supply catheter section, wherein the flow detector detects flowthrough the supply catheter section; and two or more delivery branchesin fluid communication with the distal end of the supply cathetersection, wherein each delivery branch of the two or more deliverybranches comprises a delivery catheter section comprising a proximal endand a distal end, and wherein each delivery branch of the two or moredelivery branches comprises a flow restrictor located within thedelivery branch, wherein the flow restrictor restricts flow through thedelivery catheter section; delivering fluid into the proximal end of thesupply catheter section; and monitoring the flow detector whiledelivering the fluid and while selectively occluding flow through one ormore of the supply catheter section and the delivery catheter sections.2. A method according to claim 1, wherein the flow restrictor locatedwithin each delivery branch of the two or more delivery branches islocated proximate the distal end of the delivery catheter section.
 3. Amethod according to claim 1, further comprising selectively shunting thefluid delivered into the supply catheter section outside of the systembefore the fluid enters the two or more delivery branches whilemonitoring the flow detector.
 4. A method according to claim 3, whereinthe shunting is performed using a bleeder valve in fluid communicationwith supply catheter.
 5. A method according to claim 3, wherein theshunting is performed by disconnecting the supply catheter section fromthe two or more delivery branches.
 6. A method according to claim 1,further comprising identifying an occlusion located within a specificdelivery branch of the two or more delivery branches based on monitoringthe flow detector.
 7. A method according to claim 6, wherein identifyingan occlusion located within a specific delivery branch comprisesselectively occluding all delivery branches other than the specificdelivery branch.
 8. A method according to claim 7, wherein the occludingcomprises closing a branch valve in all delivery branches other than thespecific delivery branch.
 9. A method according to claim 7, wherein theoccluding comprises manually pinching a lumen in all delivery branchesother than the specific delivery branch.
 10. A method according to claim1, further comprising identifying an occlusion located upstream of thetwo or more delivery branches based on monitoring the flow detector. 11.A method according to claim 10, wherein identifying an occlusioncomprises selectively shunting the fluid delivered into the supplycatheter outside of the system before the fluid enters the two or moredelivery branches.
 12. A method according to claim 11, wherein theshunting is performed using a bleeder valve in fluid communication withsupply catheter.
 13. A method according to claim 11, wherein theshunting is performed by disconnecting the supply catheter from the twoor more delivery branches.
 14. A method according to claim 1, furthercomprising identifying a leak located within a specific delivery branchof the two or more delivery branches based on monitoring the flowdetector.
 15. A method according to claim 14, wherein identifying a leaklocated within a specific delivery branch comprises selectivelyoccluding all delivery branches other than the specific delivery branch.16. A method according to claim 15, wherein the occluding comprisesclosing a branch valve in all delivery branches other than the specificdelivery branch.
 17. A method according to claim 15, wherein theoccluding comprises manually pinching a lumen in all delivery branchesother than the specific delivery branch.
 18. A method according to claim1, further comprising identifying a leak located upstream of the two ormore delivery branches based on monitoring the flow detector.
 19. Amethod according to claim 18, wherein identifying a leak locatedupstream of the two or more delivery branches comprises selectivelyoccluding flow through all of the two or more delivery branches.
 20. Amethod according to claim 19, wherein the occluding comprises closing abranch valve in all delivery branches of the two or more deliverybranches.
 21. A method according to claim 19, wherein the occludingcomprises manually pinching a lumen in all delivery branches of the twoor more delivery branches.
 22. A method according to claim 19, whereinselectively occluding flow through all of the two or more deliverybranches comprises occluding fluid flow proximate the distal end of thesupply catheter section.
 23. A method according to claim 22, whereinoccluding fluid flow proximate the distal end of the supply cathetersection comprises closing a supply valve.
 24. A method according toclaim 22, wherein occluding fluid flow proximate the distal end of thesupply catheter comprises manually pinching a lumen in the supplycatheter.
 25. A method of diagnosing flow conditions in a branchedcatheter system, the method comprising: providing an implantablebranched catheter system comprising: a supply catheter sectioncomprising a proximal end and a distal end, wherein moving from theproximal end towards the distal end defines a downstream directionwithin the system and wherein moving from the distal end towards theproximal end defines an upstream direction within the system; a flowdetector located proximate the proximal end of the supply cathetersection, wherein the flow detector detects flow through the supplycatheter section; and two or more delivery branches in fluidcommunication with the distal end of the supply catheter, wherein eachdelivery branch of the two or more delivery branches comprises adelivery catheter section comprising a proximal end and a distal end,and wherein each delivery branch of the two or more delivery branchescomprises a flow restrictor located proximate a distal end of thedelivery branch, wherein the flow restrictor restricts flow through thedelivery catheter section; delivering fluid into the proximal end of thesupply catheter section; monitoring the flow detector while deliveringthe fluid and while selectively occluding flow through one or more ofthe supply catheter section and the delivery catheter sections; andselectively shunting the fluid delivered into the supply cathetersection outside of the system before the fluid enters the two or moredelivery branches while monitoring the flow detector.